Radiation image information reading apparatus with radiation conversion panel, and method of correcting sensitivity of radiation conversion panel

Abstract

Corrective image data obtained by reading a stimulable phosphor sheet which is uniformly irradiated with a radiation are masked, and added and averaged into reference data. The ratio between the reference data and the corrective image data is generated as sensitivity correcting data. Desired radiation image information is then read from the stimulable phosphor sheet, corrected by the sensitivity correcting data, and outputted to an external image processing apparatus.

1. A radiation image information reading apparatus for reading radiation image information from a radiation conversion panel irradiated with a radiation, comprising:
 a corrective data calculator for calculating sensitivity correcting data for correcting a sensitivity drop of said radiation conversion panel based on radiation image information obtained by reading said radiation conversion panel which has been irradiated with the radiation; 
 a corrective data memory for storing said sensitivity correcting data; and 
 a sensitivity corrector for correcting the radiation image information read from said radiation conversion panel with said sensitivity correcting data; 
 wherein said corrective data calculator has a reference data setting unit for setting reference data with respect to image data of the radiation image information obtained by reading said radiation conversion panel which has been irradiated with the radiation, and said corrective data calculator calculates said sensitivity correcting data from said image data and said reference data. 
 
     
     
       2. A radiation image information reading apparatus according to  claim 1 , wherein said reference data setting unit sets average data of said image data as said reference data. 
     
     
       3. A radiation image information reading apparatus according to  claim 1 , wherein said reference data setting unit sets said reference data from cumulative frequencies of the respective image data. 
     
     
       4. A radiation image information reading apparatus according to  claim 1 , wherein said reference data setting unit sets said reference data from smoothed data produced by smoothing said image data. 
     
     
       5. A radiation image information reading apparatus according to  claim 1 , wherein said reference data setting unit determines and sets said reference data from said radiation conversion panel. 
     
     
       6. A radiation image information reading apparatus according to  claim 5 , wherein said reference data setting unit sets a plurality of reference data corresponding to usage conditions from said radiation conversion panel, and selects one of said reference data corresponding to actual usage conditions for generating said sensitivity correcting data. 
     
     
       7. A radiation image information reading apparatus according to  claim 1 , wherein said corrective data calculator calculates the sensitivity correcting data corresponding to usage conditions for said radiation conversion panel. 
     
     
       8. A radiation image information reading apparatus according to  claim 1 , further comprising:
 a corrective data compressor for compressing said sensitivity correcting data and storing the compressed sensitivity correcting data in said corrective data memory. 
 
     
     
       9. A radiation image information reading apparatus according to  claim 1 , further comprising:
 a sensitivity drop decision unit for determining the sensitivity drop of said radiation conversion panel based on a time for which said radiation conversion panel has been used. 
 
     
     
       10. A radiation image information reading apparatus according to  claim 1 , further comprising:
 a sensitivity drop decision unit for determining the sensitivity drop of said radiation conversion panel based on the number of times that said radiation conversion panel has been irradiated with the radiation and/or the irradiation dose of the radiation applied to said radiation conversion panel. 
 
     
     
       11. A radiation image information reading apparatus according to  claim 1 , further comprising:
 a sensitivity drop decision unit for determining the sensitivity drop of said radiation conversion panel; and 
 an indication unit for indicating a determined result from said sensitivity drop decision unit. 
 
     
     
       12. The apparatus of  claim 11 , comprising a chronological information memory storing information related to radiation exposure information corresponding to the radiation conversion panel, the radiation exposure information being updated with each use of the radiation conversion panel, and said sensitivity drop decision unit determines the sensitivity drop based on the radiation exposure information. 
     
     
       13. The apparatus of  claim 12 , said chronological information memory further storing information relating to lapse of time from manufacture for said radiation conversion panel, and said sensitivity drop decision unit determines the sensitivity drop based on the lapse of time from manufacture. 
     
     
       14. The apparatus according to  claim 1 , wherein the sensitivity drop is determined from multiple pixels of the image information. 
     
     
       15. The apparatus according to  claim 1 , wherein the sensitivity drop varies over time, and said corrective data calculator automatically determines the sensitivity correction data to account for the variation. 
     
     
       16. The apparatus of  claim 1 , wherein the radiation conversion panel stores at least one of x-ray, α-ray, β ray, ultra violet, electron beam and γ ray radiation. 
     
     
       17. The apparatus of  claim 1 , wherein the sensitivity correcting data for a two-dimensional radiation conversion panel are calculated. 
     
     
       18. The apparatus of  claim 1 , wherein the sensitivity corrector also corrects the radiation image information based partially on data that has been previously stored in addition to said sensitivity correcting data. 
     
     
       19. The apparatus of  claim 1  wherein the reading apparatus includes a photosensor, and a shading corrector to take into account sensitivity variation in the photosensor. 
     
     
       20. A radiation image information reading apparatus according to  claim 1 ,
 wherein said reference data are set based on said image data of an area in said radiation conversion panel, where sensitivity suffers a small drop. 
 
     
     
       21. A method of correcting the sensitivity of a radiation conversion panel in a radiation image information reading apparatus for reading radiation image information from the radiation conversion panel irradiated with a radiation, comprising the steps of:
 applying the radiation to said radiation conversion panel; 
 setting reference data with respect to image data of the radiation image information obtained by reading said radiation conversion panel; 
 calculating sensitivity correcting data for correcting a sensitivity drop of said radiation conversion panel based on said image data and said reference data; and 
 applying the radiation to said radiation conversion panel and correcting radiation image information obtained from said radiation conversion panel with said sensitivity correcting data. 
 
     
     
       22. A method according to  claim 21 , wherein said reference data are calculated from average data of said image data obtained by applying the radiation uniformly to said radiation conversion panel. 
     
     
       23. A method according to  claim 21 , wherein said reference data are calculated from cumulative frequencies of said image data obtained by applying the radiation uniformly to said radiation conversion panel. 
     
     
       24. A method according to  claim 21 , wherein said reference data are calculated from smoothed data produced by smoothing said image data obtained by applying the radiation uniformly to said radiation conversion panel. 
     
     
       25. A method according to  claim 21 , wherein said reference data are set from said radiation conversion panel. 
     
     
       26. A method according to  claim 25 , wherein said reference data are set as a plurality of reference data corresponding to usage conditions from said radiation conversion panel, and one of said reference data corresponding to actual usage conditions is selected for generating said sensitivity correcting data. 
     
     
       27. A method according to  claim 21 , wherein said reference data are calculated so as to correspond to usage conditions for said radiation conversion panel. 
     
     
       28. A method according to  claim 21 , further comprising the steps of:
 compressing and holding the calculated sensitivity correcting data; and 
 expanding the compressed sensitivity correcting data; 
 wherein said radiation image information is corrected using the expanded sensitivity correcting data. 
 
     
     
       29. A method according to  claim 21 ,
 wherein said reference data are set based on said image data of an area in said radiation conversion panel, where the sensitivity suffers a small drop. 
 
     
     
       30. A radiation image information reading apparatus for reading radiation image information from a radiation conversion panel irradiated with a radiation, comprising:
 a corrective data calculator for calculating sensitivity correcting data for correcting a sensitivity drop of said radiation conversion panel based on radiation image information obtained by reading said radiation conversion panel which has been irradiated with the radiation; 
 a corrective data memory for storing said sensitivity correcting data; and 
 a sensitivity corrector for correcting the radiation image information read from said radiation conversion panel with said sensitivity correcting data. 
 
     
     
       31. A radiation image information reading apparatus according to  claim 30 ,
 wherein reference data are set based on image data of an area in said radiation conversion panel, where sensitivity suffers a small drop.